The present invention relates to a chassis, especially to a chair chassis for offering users with different weights comfort and reducing vibration and abrasion while reclining chair backs of chairs.
Generally, a chair chassis includes a plurality of components such as an upper support tray, a lower support rod, a shaft, springs, etc. The upper support tray is fixed with and connected to a chair back so that the chair back is adjusted and reclined to different angles around the shaft. Thus the chair with adjustable recline angles makes users feel more comfortable and relaxed. Refer to Chinese Pat. CN 2587252Y, a support tray for chairs revealed includes a torsion spring so as to adjust the chair back. For users with different weights, various torsion springs are required. Thus the applicability is limited. Moreover, while reclining the chair back, noises are created due to friction of a brake part. And once the chair back is turned back quickly, users sense the vibration of the chair chassis and feel uncomfortable.